C-Reactive protein (CRP) is an acute phase protein. Its serum levels can of CRP increase by as much as 2000-fold during the first twenty-four hours following the onset of inflammation. A serum protein closely related to CRP, SAP, has no known function. A common property shared by CRP and SAP is their ability to bind fibronectin in a calcium-dependent manner. This property may lead to a clearer understanding of functions for both proteins. Using techniques, including cell attachment assays, tissue culture, peptide synthesis and immunoassay, a peptide from the primary sequence of SAP was found to support attachment of cells to plastic. This attachment occurs through binding to fibronectin on cells. Incubation of low levels of peptide with plastic results in enough peptide binding to support attachment of fibronectin-containing cells.